Steam generating systems are used in plants and similar industrial areas to produce steam which will be used for a plethora of different purposes. Plants that use steam as an energy source are often referred to as steam plants.
Conventional steam generators include a boiler or burner system that will produce heat around pipes carrying water thus transformed from liquid-phase to gazeous-phase. It takes some time to initiate a conventional high-output heat generating system. The initiation of a steam generating system is hereby defined as heating the steam generating system from a cold condition to a temperature that allows steam to be outputted at a desired industrial flow rate. As is known in the art, the cold condition of a steam generating system refers to its initial condition where the burner is not operational and where the boiler tubes are not at operating pressure and temperature values, or more generally where the steam generating system is not yet operational, i.e. it is not in steam production mode. The steam generating system initiation time, which thus includes a warm-up time, can be for example 30 to 60 minutes or more. If the steam generating system becomes inoperative due to some mechanical failure, then another back-up or auxiliary steam generating system may be provided to take up the steam generating task; however, waiting 30 to 60 minutes for the auxiliary steam generating system to be initiated is unacceptable since the plant operations cannot wait that long. One alternative is to have the auxiliary steam generating system operating at all times at low firing rate (low load), which is expensive and very energy inefficient (uselessly consumes resources).
It is noted that the 30 to 60 minutes of time to initiate a conventional boiler or heat generating system is usually not related to the steam output flow (debit) rate. Indeed, this initiation delay relates mostly to the time that is required to accommodate the thermally-induced mechanical stresses in the structure of the boiler. By heating the water at high temperatures through the boiler tubes, the latter are subjected to very important temperature gradients which stress the structure through its thermal expansion; furthermore, the water itself, when vaporized into steam, is the object of a very significant volumetric increase. Both of these physical phenomena require that the temperature gradients be managed diligently to prevent mechanical failure of the boiler, and this management includes delaying the vapor production over time, usually over about one hour, before the boiler may operate in a normal industrial steam production mode.